1. Field of the Invention
Embodiments of the invention relate to fasteners in general, and in particular to a contained ceramic fastener.
2. Discussion of Related Art
Ion implantation is a process of depositing chemical species into a substrate by bombardment of the substrate with energized ions. In semiconductor manufacturing, ion implanters are used for doping processes that alter the type and level of conductivity of target materials. A precise doping profile in an integrated circuit (IC) substrate and its thin-film structure is important for proper IC performance. To achieve a desired doping profile, one or more ion species may be implanted in different doses and at different energy levels.
FIG. 1 depicts an ion implanter system 1. The ion implanter 100 includes a power source 101, an ion source 102, extraction electrodes 104, a 90° magnet analyzer 106, a first deceleration (D1) stage 108, a 70° magnet analyzer 110, and a second deceleration (D2) stage 112. The D1 and D2 deceleration stages (often referred to as “deceleration lenses”) are each comprised of multiple electrodes with a defined aperture to allow an ion beam to pass therethrough. By applying different combinations of voltage potentials to the multiple electrodes, the D1 and D2 deceleration lenses may manipulate ion energies and cause the ion beam to hit a target workpiece 114 at a desired energy. A number of measurement devices 116 (e.g., a dose control Faraday cup, a traveling Faraday cup, or a setup Faraday cup) may be used to monitor and control the ion beam conditions. Although not shown in FIG. 1, the target workpiece 114 may be supported by a platen which can be used to fix and to move the workpiece during implantation.
It has been discovered that for some silicon wafer workpieces, a relatively low temperature during ion implantation can be advantageous for amorphization of the silicon wafer. For example, performing ion implantation at temperatures below −60° Celsius (C) may substantially improve ion implantation process performance. In ion implantation applications, wafers are typically cooled during the implantation process by a cryogenic liquid supplied to a cooling platen, where the cryogenic liquid has been cooled by a chiller.
In other ion implantations processes, the desired doping profile is achieved by implanting ions in the target substrate at high temperatures (e.g., between 150-600° C.) Heating the target substrate can be achieved by supporting the substrate on a heated platen during the ion implant process.
A platen is typically used to clamp the substrate during implant and provide wafer heating or cooling. As such, the platen and its associated components must be able to withstand large temperature shifts. The fasteners used to fix elements of the platen must, therefore, be able to withstand these large temperature shifts while still maintaining desired fastening forces.
Ceramic fasteners are known for use in high temperature applications. While known ceramic fasteners can withstand desired high temperatures and maintain desired fastening forces, they suffer from the problem that they have the tendency to fail in a catastrophic manner when subject to high installation torques. This failure mode is undesirable because it often results in the uncontrolled dispersal of ceramic pieces and particles in the work area. Thus, there is a need for an improved ceramic fastener design for use in coupling components of semiconductor processing platens.